EP3788514A1 - Procede de simulation du comportement physique d'un pneu et application a la simulation en temps reel - Google Patents
Procede de simulation du comportement physique d'un pneu et application a la simulation en temps reelInfo
- Publication number
- EP3788514A1 EP3788514A1 EP19728493.8A EP19728493A EP3788514A1 EP 3788514 A1 EP3788514 A1 EP 3788514A1 EP 19728493 A EP19728493 A EP 19728493A EP 3788514 A1 EP3788514 A1 EP 3788514A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- slice
- steering angle
- coefficient
- contact
- tire
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/10—Geometric CAD
- G06F30/15—Vehicle, aircraft or watercraft design
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F30/00—Computer-aided design [CAD]
- G06F30/20—Design optimisation, verification or simulation
- G06F30/23—Design optimisation, verification or simulation using finite element methods [FEM] or finite difference methods [FDM]
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2111/00—Details relating to CAD techniques
- G06F2111/10—Numerical modelling
-
- G—PHYSICS
- G06—COMPUTING; CALCULATING OR COUNTING
- G06F—ELECTRIC DIGITAL DATA PROCESSING
- G06F2119/00—Details relating to the type or aim of the analysis or the optimisation
- G06F2119/14—Force analysis or force optimisation, e.g. static or dynamic forces
Definitions
- the invention relates broadly to techniques related to the equipment of tires (or tires) of motor vehicles. More particularly, it relates to a method for simulating the physical behavior of a tire fitted to a vehicle that is stationary or almost stationary on the ground with which the tire tread has an area of contact including an adherent contact zone. and a sliding contact zone, the vehicle having a steering angle likely to vary during the simulation.
- the invention also relates to the application of the method of the invention to the simulation in real time of the dynamic behavior of a vehicle equipped with at least one tire.
- the invention is part of a development of TameTire software (trademark of the Michelin company) implementing a method of simulating the physical behavior of a tire fitted to a vehicle while taxiing on the ground.
- the method is described in detail in patent document FR 2 905 496.
- the method makes it possible in particular to calculate in real time longitudinal forces, transverse forces and a self-alignment torque of the tire.
- the self-aligning torque is the torque exerted on the tire at the interface with the ground, around an axis Z passing through the center of the contact area, orthogonal to the ground surface and pointing to the top.
- the TameTire software did not initially offer a reliable simulation of the physical behavior of the tire in a stall situation or at a standstill, or in a transitional phase between stopping and driving the vehicle.
- an object of the invention is to propose a simulation of the behavior of the tire in a steering situation at a standstill or almost at a standstill as well as in a situation of transition to rolling that takes into account the characteristic physical parameters. of the tire and that is compatible with a real-time application.
- the invention relates to a method for simulating the physical behavior of a tire fitted to a vehicle that is stationary or almost stationary on the ground with which the tire tread has an area of contact including an adhering contact zone. and a sliding contact area, the method being implemented by a computer, the vehicle having a varying steering angle during the simulation, which method is characterized by comprising the following steps for calculating a resultant force transmitted by the tire between the ground and the vehicle at a given moment modeling of the contact area in the form of a square surface,
- the term vehicle when stopped or almost stopped a vehicle having a speed below a speed threshold, for example 0.1 m / s.
- a speed threshold for example 0.1 m / s.
- Such a method provides an aid to the design of the tires in that it allows a fine modeling of the forces transmitted by the tire between the ground and the vehicle in the framework of maneuvers at rest or almost at a standstill, for example in a maneuver to park the vehicle.
- the modeling of the forces transmitted by the tire between the ground and the vehicle also makes it possible to deduce the forces transmitted to the steering wheel in a maneuver.
- the method when the method is coupled to a modeling of the vehicle, for example in a driving simulator, it can constitute an aid to the design of the steering systems.
- the process allows a particularly fine modeling of efforts because it finely models the tire taking into account the characteristic physical parameters of the tire.
- the method of the invention makes it possible to connect the design parameters of a tire with a resultant data without the need to measure the tire on a test machine.
- the contact area having a substantially rectangular shape of length L and width I
- the square surface modeling the contact area has sides of dimension (L + 1) / 2 corresponding to the average of the length L and the width I.
- a discretization of the contact area in a single direction makes it possible, with respect to a discretization according to two orthogonal directions between them, to reduce the calculation time but proves unsatisfactory in the absence of modeling in the form of a square surface in the case of wide tires, hence the proposed step of moving to a square-shaped contact area.
- the resulting calculated stress models a self-aligning torque.
- the modeling of the self-alignment torque makes it possible to determine the forces coming from the ground on the tire and that can be transmitted to the steering wheel through the direction of the vehicle. Thus, this can better define the force and torque constraints that support a power steering.
- the steering angle considered is the steering angle with respect to a corresponding initial steering angle:
- the determination of the nature of the contact, adhering or sliding, between the edge and the ground is performed as a function of the absolute value of the steering angle and its direction of variation. This is a simple and reliable way to determine the nature of the contact.
- the determination of the nature of the contact, adhering or sliding, between the wafer and the ground comprises the comparison of the absolute value of the steering angle with a threshold value calculated specifically for each wafer.
- the determination of the nature of the contact, adhering or sliding, between the wafer and the ground determines that:
- the threshold value calculated specifically for each slice is:
- the calculated elementary forces for modeling the self-alignment torque are:
- the elementary forces calculated for modeling the self-alignment torque are:
- the resulting effort is calculated from the sum:
- the resulting effort is calculated from a coefficient of adhesion obtained by the sum:
- a first term corresponding to a coefficient of adhesion in a hypothesis of stopping the vehicle, the first term being weighted by a first variable coefficient between 0 and 1 and exponentially decreasing with the distance traveled since stopping,
- the invention also relates to the application of the method of the invention to the simulation in real time of the dynamic behavior of a vehicle equipped with at least one tire.
- Real-time simulation allows the process to be integrated into a driving simulator.
- the dynamic parameters derived from the driving simulator reflect the reality more accurately than a simple mathematical model. The simulation obtained is therefore particularly fine.
- FIG. 1 represents a flowchart of a method according to one embodiment of the invention
- Figure 2a shows a schematic view of a contact area of a tire
- Figure 2b shows a square surface modeling the contact area of Figure 2a
- FIG. 3 represents a discretization of the square surface of Figure 2b by slicing
- Fig. 4 is a graph showing the value of the self-aligning torque (Mz) as a function of the value of the actual steering angle
- FIGS. 5a and 5b show the contact area of FIG. 2a respectively in an initial state with an initial steering angle and in a stopping state with respect to the initial steering angle;
- Figure 6 is a graph showing the threshold value of the steering angle for a wafer as a function of the abscissa of the wafer.
- FIG. 1 represents a flowchart of a method according to one embodiment of the invention.
- the method comprises:
- a determination Ec is made of the nature of the contact, adhering or sliding, between the slice and the ground as a function of the steering angle
- Figures 2a and 2b illustrate the first modeling step Ea of the contact area in the form of a square surface.
- Figure 2a shows a contact area S having a substantially rectangular shape of length L and width I.
- the length L of the contact area S is aligned with the direction of advance of the tire represented by the axis X0.
- the contact area S is modeled by a square surface S 'represented in FIG. 2b and having sides of dimension (L + 1) / 2 corresponding to the average of the length L and of the width I of the area of contact S.
- the square surface S ' comprises two sides aligned with the length of the contact area S and two sides aligned with the width of the contact area S. This modeling is equivalent, from a point of view of the self-alignment torque when stopped or almost stopped, at the actual contact area.
- FIG. 3 represents a discretization Eb of the square surface S 'of FIG. 2b by slicing T according to the second step of the method of the invention.
- the slices T obtained are rectangular. They have a dimension length (L + 1) / 2 orthogonal to the direction of travel and a width dr in the direction of travel.
- Each slice T is marked by the abscissa r of its center on the axis X0, the null abscissa being fixed at the center of the square surface S '.
- the zero abscissa point corresponds to the pivot point of the tire when the steering is stationary.
- the third step of the method is detailed in the following. This step comprises, for each slice, a determination Ec of the nature of the contact, adhering or sliding, between the slice T and the ground according to the steering angle.
- Fig. 4 is a graph showing the value of the auto-alignment torque Mz as a function of the actual real steering angle Q value in a steering cycle.
- the actual steering angle is the angle between the wheel orientation and the vehicle axis. Conventionally, the actual steering angle increases when the driver steers to the right and decreases when the driver turns to the left; the self-aligning torque is positive when it is clockwise with respect to an axis Z passing through the center of the contact area, orthogonal to the ground surface and pointing to the top, and the self-aligning torque is negative when it is anti-clockwise with respect to the Z axis. Note that this corresponds to a non-direct reference system ( positive angle when rotating clockwise).
- the self-alignment torque has a zero value for a zero real steering angle. From point A, the driver steers to the right and the absolute value of the self-aligning torque increases with the actual steering angle. Then, from point B, the driver counterbrakes to the left and the steering angle decreases, which causes a fall in the absolute value of the self-aligning torque.
- the cycle shown shows a hysteresis phenomenon insofar as the self-alignment torque vanishes again at a point C distinct from point A. At point C, the steering angle has an offset value. positive. Between point A and point C, the self-alignment torque has positive values.
- the curve of the graph can be broken down into four types of phases.
- a first phase 1 In a first phase 1, called the quasi-linear phase, the torque Mz increases proportionally to the steering angle Q.
- the tire is in contact with the ground over the entire contact area, the tread rubber is sheared and the tire twists.
- transition In a second phase 2, called transition, the increase in the torque Mz with the steering angle ⁇ is less strong. A growing portion of the tread slips, the maximum shear of the gum is reached. The tire continues to twist.
- a third phase 3 called saturation
- the torque Mz does not increase any more with the steering angle Q.
- the tire saturates at the shear of the tread and therefore slips on almost the entire contact area .
- the maximum torsion is reached.
- a fourth phase 4 called de-shearing
- the wheel is pointed in the other direction, the torque Mz decreases sharply with the decrease of the angle Q.
- the tire recovers and the shear falls almost linearly over all the contact area and vanishes for a steering angle value, referred to as the slip angle.
- the graph of FIG. 4 thus makes it possible to determine the nature of the contact, adhering or sliding, between the slice T and the ground as a function of the steering angle Q.
- FIG. 5a shows the contact area of FIG. 2a in an initial state with an initial steering angle qo applied at the last moment of zero self-alignment torque.
- the initial steering angle qo corresponds to the slip angle described above. Otherwise, the initial steering angle qo corresponds to the steering angle applied at the last moment of non-zero speed.
- Figure 5b shows the contact area in a stopping state with respect to the initial steering angle.
- the direction of advance of the tire is represented by the axis X0 and in the steering state, the direction of advance of the tire is represented by the axis Xt.
- the angle formed between the axis X0 and the axis Xt is the steering angle Q.
- the steering angle Q considered is the steering angle with respect to an initial steering angle qo taking into account the tire relaxation if there was an initial driving phase.
- the determination of the nature of the contact, adhering or slipping, between the wafer and the ground is performed according to the absolute value of the steering angle Q and its direction of variation.
- the slip is different for each "slice" of the tire.
- the offset related to the slip is different for each of the tire slices.
- the offset linked to a non-zero steering angle after a rolling phase, or to the relaxation of the tire is global, that is to say that it is the same for all the slices.
- FIG. 6 is a graph representing the threshold value ⁇ max of the steering angle for a wafer as a function of the abscissa r of the wafer.
- the graph shows that the central slices, that is to say, abscissa r close to 0, have a threshold value max max high; indeed, the threshold value max max tends to + when the abscissa r tends to 0. Therefore, the central slices are more adherent.
- the peripheral wafers that is to say the abscissa r that are not equal to 0, have a low threshold value ⁇ max; indeed, the threshold value max max tending to 0 when the abscissa tends to + or -. As a result, the edge slices are more slippery.
- the threshold value max max is given by the following equation:
- the threshold value max max is:
- the direction of variation of Q ie the steering direction, is determined by the sign of the difference between the value of the steering angle ((t + 1) at time t + 1 and the value of the steering angle ⁇ (t) at the previous instant t:
- SensV at ⁇ a ⁇ ohq sign (Q (t + 1) - 0 (t))
- the fourth step is detailed in the following.
- the calculation Ed of the elementary force acting on the slice is performed by applying predetermined equations, specific depending on the nature of the contact, adherent or sliding, and expressed as a function of parameters. dynamics (for example, the steering angle or the pressure of the tire) related to the conditions of use of the tire and according to physical parameters (for example the estimation of the lengths and widths of contact areas, the rigidity of shear of the tread, the rate of notching in the band or the stiffness of the tire) characteristics of the tire.
- dynamics for example, the steering angle or the pressure of the tire
- physical parameters for example the estimation of the lengths and widths of contact areas, the rigidity of shear of the tread, the rate of notching in the band or the stiffness of the tire
- the resulting force is calculated by integrating the elementary forces over the entire square area.
- the integration formula is as follows:
- the vehicle is considered to be stationary when its speed is below a speed threshold.
- the speed threshold is, for example, 0.1 m / s.
- a first term Mz stop corresponding to a resulting effort calculated in a hypothesis of stopping the vehicle, the first term being weighted by a first coefficient e D / D0 variable between 0 and 1 and exponentially decreasing with the distance D traveled since stop, and
- - DO is a predetermined coefficient, that is to say a numerical value fixed in advance.
- - DO ' is a predetermined coefficient, that is to say a numerical value fixed in advance.
- a second term prouiage corresponding to a coefficient of adhesion in a rolling hypothesis of the vehicle the second term being weighted by a second coefficient (1 -e D / D0 " ) variable between 0 and 1 and exponentially increasing with the distance D traveled since the stop; the sum of the first coefficient and the second coefficient being equal to 1.
- the formula used is the following:
- - DO is a predetermined coefficient, that is to say a numerical value fixed in advance.
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- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Theoretical Computer Science (AREA)
- Geometry (AREA)
- General Physics & Mathematics (AREA)
- General Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Evolutionary Computation (AREA)
- Computational Mathematics (AREA)
- Mathematical Analysis (AREA)
- Mathematical Optimization (AREA)
- Pure & Applied Mathematics (AREA)
- Aviation & Aerospace Engineering (AREA)
- Automation & Control Theory (AREA)
- Tires In General (AREA)
- Length Measuring Devices With Unspecified Measuring Means (AREA)
- Management, Administration, Business Operations System, And Electronic Commerce (AREA)
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR1853840A FR3080820B1 (fr) | 2018-05-03 | 2018-05-03 | Procede de simulation du comportement physique d'un pneu et application a la simulation en temps reel |
PCT/FR2019/051022 WO2019211570A1 (fr) | 2018-05-03 | 2019-05-03 | Procede de simulation du comportement physique d'un pneu et application a la simulation en temps reel |
Publications (1)
Publication Number | Publication Date |
---|---|
EP3788514A1 true EP3788514A1 (fr) | 2021-03-10 |
Family
ID=63407335
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP19728493.8A Withdrawn EP3788514A1 (fr) | 2018-05-03 | 2019-05-03 | Procede de simulation du comportement physique d'un pneu et application a la simulation en temps reel |
Country Status (4)
Country | Link |
---|---|
US (1) | US11809788B2 (fr) |
EP (1) | EP3788514A1 (fr) |
FR (1) | FR3080820B1 (fr) |
WO (1) | WO2019211570A1 (fr) |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP3224089B2 (ja) * | 1997-03-25 | 2001-10-29 | 日立金属株式会社 | ホイールのドラム耐久評価方法 |
US6741957B1 (en) * | 2000-07-21 | 2004-05-25 | Daimlerchrysler Corporation | Analytical tire model for vehicle durability and ride comfort analysis |
US7363805B2 (en) * | 2005-09-30 | 2008-04-29 | Ford Motor Company | System for virtual prediction of road loads |
EP1840552B1 (fr) * | 2006-03-31 | 2012-05-02 | The Yokohama Rubber Co., Ltd. | Procédé de calcul de données de réponse transitoire des pneus, procédé de conception de pneus et procédé de prédiction des mouvements du véhicule |
FR2905496B1 (fr) | 2006-09-01 | 2008-10-24 | Michelin Soc Tech | Procede de simulation en temps reel du comportement physique d'un pneu, et application |
FR3049901A1 (fr) * | 2016-04-08 | 2017-10-13 | Michelin & Cie | Bande de roulement a directionnalites differenciees pour un pneumatique pour vehicule lourd |
-
2018
- 2018-05-03 FR FR1853840A patent/FR3080820B1/fr active Active
-
2019
- 2019-05-03 EP EP19728493.8A patent/EP3788514A1/fr not_active Withdrawn
- 2019-05-03 US US17/052,670 patent/US11809788B2/en active Active
- 2019-05-03 WO PCT/FR2019/051022 patent/WO2019211570A1/fr active Application Filing
Also Published As
Publication number | Publication date |
---|---|
US20210240879A1 (en) | 2021-08-05 |
FR3080820B1 (fr) | 2023-04-21 |
FR3080820A1 (fr) | 2019-11-08 |
US11809788B2 (en) | 2023-11-07 |
WO2019211570A1 (fr) | 2019-11-07 |
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